In a factory which conducting the dry-cleaning of clothing etc., a petroleum solvent, a chlorine-based solvent, a fluorine-based solvent, etc. are used as a dry-cleaning solvent. Among these, safety of the chlorine-based solvent is regarded as questionable although the chlorine-based solvent has an advantage which washing and drying can conducted in a short time, and the fluorine-based solvent is expensive although the fluorine-based solvent has the advantage of nonflammability. Accordingly the petroleum solvent is increasingly widely used. Water- and oil-repelling treatment of clothing etc. can be conducted by using the same device and process as the dry cleaning. Therefore, it is desired that the water- and oil-repellent agent used for water- and oil-repelling treatment comprises the petroleum solvent as the solvent, or has easy dilution and dispersion into the petroleum solvent.
Hitherto, various fluorine-containing compounds are proposed. The fluorine-containing compounds have the advantageous effects of having properties excellent in heat resistance, oxidation resistance, weather resistance and the like. The fluorine-containing compounds are used as, for example, the water- and oil-repellent agent and soil release agent by utilizing the properties that the fluorine-containing compounds have low free energy, i.e., difficulty in adherence.
Examples of the fluorine-containing compounds used as the water- and oil-repellent agent include a fluorine-containing polymer having repeating units derived from (meth)acrylate ester having a fluoroalkyl group. Various up-to-date research results indicate that, in view of the practical treatment of fibers with the surface treatment agent, the important surface property is not a static contact angle, but is a dynamic contact angle, particularly a reversing contact angle. That is, the advancing contact angle of water is not dependent on the carbon number of the fluoroalkyl side chain, but the reversing contact angle of water in the case of carbon number of at most 7 is remarkably low than that in the case of carbon number of at least 8. In correspondence to this, an X ray analysis shows that the side chain crystallizes when the carbon number of side chain is at least 7. It is known that the actual water repellency has correlation with the crystallization of the side chain and that mobility of the surface treatment agent molecules is an important factor for expression of the actual performances (for example, MAEKAWA Takashige, FINE CHEMICAL, Vol. 23, No. 6, page 12 (1994)). On basis of the above-mentioned reasons, the acrylate polymer as such having low carbon number of fluoroalkyl group in the side chain which is at most 7 (particularly at most 6) has low crystallinity so that the polymer cannot satisfy the practical performances.
WO2004/096939 A1 discloses a surface treatment agent which comprises a fluorine-containing polymer formed from a fluorine-containing monomer, a monomer free from a fluorine atom, and an optionally present crosslikable monomer.
WO2008/143093 A1 discloses a masonry treatment agent which comprises a fluorine-containing polymer formed from a fluorine-containing acrylate monomer, and one or both of a monomer having a cyclic hydrocarbon group or a monomer having a short chain hydrocarbon group.
WO2006/121171 A1 discloses a surface treatment agent which comprises a fluorosilicone reaction product which comprises a mercapto-functional organopolysiloxane and a fluorine-containing monomer.
WO2004/108855 A1 discloses a surface treatment agent which comprises a fluorine-containing polymer formed from a fluorine-containing monomer, wherein (a) the fluorine-containing polymer has a silicon atom, or (b) the surface treatment agent comprises the fluorine-containing polymer (first polymer), and a second polymer that is different from the first polymer and that is a silicon-containing polymer having a silicon atom.
The treatment agents proposed by these prior art literatures would not give both of the excellent solubility (of the fluorine-containing polymer) to the petroleum solvent, and the excellent water- and oil-repellency.
The surface treatment agents, which are now industrially used and which are a solution in an organic solvent, are supposed to comprise F(CF2)6CH2CH2OCOC(CH3)═CH2 (C6SFMA), isobornyl methacrylate and stearyl methacrylate.